Microporous membrane was newly derived from P(VDF-HFP)／acetone／water system by dry-casting in the alr．The structure of microporous P(VDF-HFP) membrane was observed through SEM．It was found that the pores were distributed uniformly in the whole membrane

some pearls were attached onto the skeleton and the diameter of the pores was in the order of a few microns．The porosity of the membrane was measured up to 72％ by weighting the membrane’s mass before and after absorption of n-butanol．The crystallization behavior of the copolymer was studied with DSC before and after the formation of microporous membrane．In order to understand the morphology of the membrane

the process of the formation of micropores was discussed based on both the kinetic and thermodynamic points in the paper．The porous P(VDF-HFP) electrolyte was prepared by impregnating the membrane with PC／EC liquid electrolyte．The resistance of the solid porous electrolyte was measured by the ZL5 intelligent LCR meter

and the conductivity was evaluated from equation

σ=L／(RS)．At ambient temperature the conducting can reach 10-3S／cm. The solution holding of the porous solid electrolyte was tested by isothermal TGA measurements

which illustrate that the mass loss was only 10％ at 60℃ in the open air for 1.5 h．It shows that the porous solid electrolyte prepared by this process has the potential application in the lithium ion battery

and that this method of membrane formation is nonpoisonous to the environment．